The present invention relates generally to steering apparatuses or systems for steerable vehicles, and more particularly to a steering apparatus for a steerable vehicle which is equipped with a backup unit for selectively and mechanically connecting and disconnecting a steering unit and an operating unit.
A Published Japanese Patent Application No. 2001-171543 (hereinafter referred to as “JP2001-171543”) shows a motor-driven steering device which includes a steering wheel, a steering mechanism, a clutch for selectively connecting and disconnecting the steering wheel and the steering mechanism, a steering motor, and a feedback motor. When a steer angle of a vehicle equipped with the steering device reaches a maximum steer angle with a rack shaft being in contact with a rack stopper in a steer-by-wire mode in which the steering wheel is mechanically disconnected from the steering mechanism, a controller engages the clutch to connect the steering wheel and the steering mechanism, and sets the output torques of the feedback motor and the steering motor to zero.